A transformer is a device that is used to change alternating voltage based on the Faraday law of electromagnetic induction. A regular transformer includes a primary coil, a secondary coil, and a magnetic core (a shared magnetic field). The transformer is able to transfer electrical energy from the primary coil to the secondary coil through the first coil and the secondary coil wrapped around the magnetic core.
The basic principle of the transformer includes passing an electric current through the primary coil to induce a magnetic field (electromagnetism) in the magnetic core. Then, the electric current in the primary coil is changed to change the strength of the magnetic field in the magnetic core. Further, the changing magnetic field induces an electric current in the secondary coil sharing the same magnetic core (magnetic field) with the primary coil. Thus, the energy is transferred from the primary coil to the secondary coil.
FIG. 1 illustrates an existing transformer. As shown in FIG. 1, the transformer includes a magnetic core 100. The magnetic core 100 has a loop shape. The transformer also includes a primary coil 101 and a secondary coil 102 wrapping around the magnetic core 100. The primary coil 101 is independent of the secondary coil 102; and the primary coil 101 is electrically isolated from the secondary coil 102. When a voltage is applied on both ends (“+” and “−”) of the primary coil 101, an electrical current is passing through the primary coil 101. The current induces a magnetic field in the magnetic core 100. If the voltage is an alternating voltage, the magnetic field in the magnetic core 100 is also an alternating magnetic field. The alternating magnetic field is able to induce an electric potential between the two ends (“+” and “−”) of the secondary coil 102. When a load is connected with the two ends of the secondary coil 102, an electric current is generated in the secondary coil 102.
However, such transformer may not have a desired stability. The disclosed device structures and methods are directed to solve one or more problems set forth above and other problems.